Structural integrity of bridges degrades with time due to environmental conditions. Exposure of bridge structures to harmful materials such as salts promotes oxidation of steel components of such structures. Such oxidation may be due to direct exposure of a bridge structure to harmful material such as chlorides in the salts or it may be due to slow infiltration of chlorides into reinforced concrete sections. Chlorides can corrode the reinforcing steel rebar in concrete bridge decks, requiring regular maintenance to ensure the health and safety of bridges. Although the diffusion rate of chlorides may be slow, the resulting corrosion can expand the volume of reinforcing bars (rebars) of the structure and cause the surrounding concrete to crack. Unless preventive maintenance is performed regularly, bridge life spans can be significantly shortened. Detection of corroding rebar in concrete may be difficult, and efforts to remedy such corrosion may be difficult without performing extensive rebuilding of the structure.
Acquiring knowledge as to when and where to perform such maintenance has typically been a costly and time-consuming process. Current methods for analyzing the levels of chlorides in bridge decks involve extracting concrete core samples and analyzing them in a laboratory setting, which is laborious and time consuming. Many tests are required, since it typically takes several years for critical chloride concentration levels to be reached. During bridge inspection, lanes are typically closed, and the bridge is usually sampled only at a few points along the deck. Accordingly, monitoring costs to identify deterioration of bridge structures can be significant.
Thus, it is desirable to develop improved sensor technologies to overcome the above-noted problems.